Low profile converters are a particular area of interest in connection with LED lighting. Planar transformers and high frequency operation are associated with this.
Previous reports have highlighted the problems of operating a converter at high frequencies with an associated high voltage.
The German patent application DE 102 04 433 A1 teaches a direct voltage converter such as an electronic power supply unit for gas discharge lamps that is supplied with a rectified mains voltage and produces a converted controlled direct voltage. The direct voltage converter comprises a high frequency power inverter and a series resonant circuit, wherein the high frequency power inverter applies to the series resonant circuit a high frequency alternating voltage. The high frequency of the high frequency power inverter is within the range of the resonant frequency of the series resonant circuit. Further, an output rectifier produces a controlled rectified output voltage, wherein the control of the output voltage is performed by feeding the output voltage back to a control unit that controls the switches of the high frequency power inverter.
The European patent document EP 2 225 918 B1 discloses a circuit for an electrically isolated generation of an output voltage starting from a mains voltage, wherein the circuit comprises a power factor correction circuit with an inductor, which is supplied with the mains voltage, and with a controllable switch for controlling the charging and discharging of the inductor. Furthermore, the circuit comprises at least one potential separation transformer for galvanic isolation of the output voltage from the mains voltage, wherein at the time of discharging the inductor a first part of the energy stored by the inductor during the charging is directly supplied to the potential separation transformer.
In the light of the prior art, it is an object of the present invention to provide an improved operation device for lighting means that can achieve PFC functionality when operated at high frequency and high voltages.
This object is achieved by an operation device and a lighting device according to the invention described below.